Strategic modular refrigeration system with linear compressors

ABSTRACT

A modular commercial refrigeration unit constructed and arranged for placement in strategic proximity to a plurality of associated product cooling zones within a shopping area includes a refrigeration rack proximate to a shopping area and configured to accommodate maximum refrigeration loads of the associated product cooling zones. The refrigeration rack has an optimum footprint. The refrigeration rack is constructed to support components of a closed refrigeration circuit including associated high side and low side refrigerant delivery and suction means extending from the rack and being operatively connected to a plurality of evaporators for cooling the associated product cooling zones. The modular refrigeration unit also includes a linear compressor and a cooling source remote from the refrigeration unit that provides a cooling relationship with a condenser for providing optimum condensing and efficiency of the evaporators in cooling the associated product cooling zones.

BACKGROUND

The present invention relates to commercial refrigeration systems, and in particular, commercial refrigeration systems having at least one linear compressor.

Commercial refrigeration systems have traditionally been accomplished via centralized parallel compressor systems with long liquid and suction branches piped to and from the evaporators in the refrigerated display cases. As an alternative, centralized parallel rack refrigeration systems have been developed for cooling a plurality of fixtures in multiple cooling zones within a shopping area. Another alternative is a self-contained, refrigeration display merchandiser including multiple horizontal scroll compressors.

A disadvantage to all these systems is the use of scroll compressors within the commercial refrigeration systems. Scroll compressors generate too much acoustic noise for the shopping area of a store and do not allow for variable capacity control of the refrigeration system. Because of the lack of variable capacity control, the compressor may perform unnecessary cycling, which may be detrimental to the stored commodity (e.g., sensitive food products) refrigerated by the merchandisers or refrigerated display cases. Further, scroll compressors use oil for operation, which results in inefficient performance due to oil film on evaporator and condenser surfaces, requires the use of expensive oil management components, and increases the installation cost of the refrigeration system.

It would be beneficial to have another alternative to the above systems and units utilizing scroll compressors.

SUMMARY

In one embodiment, the invention provides a modular commercial refrigeration unit constructed and arranged for placement in strategic proximity to a plurality of associated product cooling zones within a shopping area. The modular refrigeration unit includes a refrigeration rack proximate to a shopping area and configured to accommodate maximum refrigeration loads of the associated product cooling zones. The refrigeration rack has an optimum footprint. The refrigeration rack is constructed to support components of a closed refrigeration circuit including associated high side and low side refrigerant delivery and suction means extending from the rack and being operatively connected to a plurality of evaporators for cooling the associated product cooling zones. The modular refrigeration unit also includes a linear compressor and a cooling source remote from the refrigeration unit that provides a cooling relationship with a condenser for providing optimum condensing and efficiency of the evaporators in cooling the associated product cooling zones.

In another embodiment, the invention provides a modular refrigeration system including at least two refrigerated fixtures having first closely adjacent locations in a shopping area, at least one evaporator coil for cooling the refrigerated fixtures to maintain products therein within a predetermined temperature range, a linear compressor having a second location in close proximity to the refrigerated fixtures, and a condenser connected together with the linear compressor and the evaporator coils to form a closed loop refrigeration circuit. The modular refrigeration system also includes a heat exchange device located remote from the shopping area for transferring heat to an exterior atmosphere, and a closed heat transfer loop extending between the closed loop refrigeration circuit and the remote environment and interconnecting the heat exchange device and the condenser in continuous communication to transfer heat from the condenser to the heat exchange device.

In still another embodiment, the invention provides a commercial refrigeration network including a first modular refrigeration system unit in close strategic proximity to a first refrigerated product zone. The first modular refrigeration system unit includes a first refrigeration rack having first closed refrigeration circuit components including a linear compressor, high side receiver means and associated high side and low side refrigerant delivery, and suction means operatively connected to a first evaporator for cooling the first refrigerated zone. The first modular refrigeration system unit also includes a first condenser connected between the linear compressor and receiver means of the first closed refrigeration circuit. The commercial refrigeration network also includes at least one other modular refrigeration system unit in close strategic proximity to an associated other refrigerated product zone. The at least one other modular refrigeration system includes an other refrigeration rack having other closed refrigeration circuit components including a linear compressor, high side receiver means and associated high side and low side refrigerant delivery, and suction means operatively connected to an other evaporator for cooling the other refrigerated zone. The other modular refrigeration system unit also includes an other condenser connected between the linear compressor and receiver means of the other closed refrigeration circuit. Further, the commercial refrigeration network also includes a cooling source remote from the refrigeration unit that provides a cooling relationship with the first and other condensers for the respective first and other refrigeration system units.

In a further embodiment, the invention provides a commercial refrigeration network including a first refrigeration merchandiser, at least one other refrigeration merchandiser, and a cooling source. The first refrigeration merchandiser includes at least one first surface at least partially defining a first environmental space adapted to accommodate a commodity, first closed refrigeration circuit components, and a first frame. The first closed refrigeration circuit components include a free-piston linear compressor, a condenser, an expansion device, and an evaporator in fluid communication wherein the evaporator is in thermal communication with the environmental space to influence the temperature of the environmental space. The first frame supports the at least one first surface, the linear compressor and the evaporator. The at least one other refrigeration merchandiser includes at least one other surface at least partially defining an other environmental space adapted to accommodate a commodity, other closed refrigeration circuit components, and an other frame. The other closed refrigeration circuit components include a free-piston linear compressor, a condenser, an expansion device, and an evaporator in fluid communication wherein the evaporator is in thermal communication with the environmental space to influence the temperature of the environmental space. The other frame supports the at least one other surface, the linear compressor and the evaporator. The cooling source remote from the refrigeration unit provides a cooling relationship with the first and other condensers for the respective first and other refrigeration system units.

Other aspects and advantages of the invention will become apparent by consideration of the detailed description, claims and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a modular commercial refrigeration network embodying the invention.

FIG. 2 is a schematic flow diagram of a modular refrigeration system unit and coolant circulating system.

FIG. 3 is a schematic flow diagram of a refrigeration system unit and coolant circulating system located remotely from the respective refrigeration loads.

FIG. 4 is a schematic flow diagram of a modular refrigeration system unit with an air cooled condenser.

FIG. 5 is a representative supermarket floor plan illustrating the strategic placement of dedicated modular refrigeration system units relative to the respective refrigeration loads and positioned remotely of the respective refrigeration loads.

FIG. 6 is a sectional view of a dual opposing, free-piston linear compressor used in a refrigeration unit, which shows the compressor at an intake stroke.

FIG. 7 is a sectional view of a dual opposing, free-piston linear compressor used in a refrigeration unit, which shows the compressor at neutral.

FIG. 8 is a sectional view of a dual opposing, free-piston linear compressor used in a refrigeration unit, which shows the compressor at a compression stroke.

FIG. 9 is an enlarged supermarket floor plan illustrating a department with a dedicated modular refrigeration unit having multiple linear compressors.

FIG. 9A is a top plan view of the refrigeration unit of FIG. 9 illustrating a heat exchanger network with a cooling liquid source.

FIG. 10 is an enlarged supermarket floor plan illustrating a department with merchandisers and a dedicated refrigeration unit having multiple linear compressors located remotely from the merchandisers.

FIG. 11 is a diagrammatic perspective view showing an open front refrigerated merchandiser lineup and associated vertical modular refrigeration unit.

FIG. 12 is another diagrammatic perspective view showing a lineup of reach-in merchandisers strategically incorporating a vertical modular refrigeration unit.

FIG. 13 is a plan view of a lineup of wide island cases showing a linear compressor arrangement in the associated modular refrigeration unit.

FIG. 14 is a plan view of a lineup of wide island cases with an associated refrigeration unit including multiple linear compressors located remotely of the wide island cases.

FIG. 15 is a diagrammatic side elevational view illustrating a modular refrigeration rack for a refrigeration unit with multiple linear compressors.

FIG. 15A is a diagrammatic plan view of the modular refrigeration rack of FIG. 15.

FIG. 16 is a perspective view of two refrigeration merchandisers and further showing elements of the refrigeration cycle of the merchandisers.

Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings.

For purposes of disclosure, the term “high side” is used herein in a conventional refrigeration sense to mean a portion of a system from the compressor discharge to the evaporator expansion valves, and the term “low side” means the portion of the system from the expansion valves to the compressor suction. Also, “low temperature” as used herein shall have reference to evaporator temperatures in the range of about −35° F. to about −5° F., or the associated product temperatures in the range of about −20° F. to about 0° F. Further, “normal temperature” as used herein means evaporator temperatures in the range of about 15° F. to about 40° F., or the associated non-frozen product temperatures in the range of about 25° F. to about 50° F. “Medium temperature” is also used interchangeably for “normal temperature” in the refrigeration industry.

DETAILED DESCRIPTION

FIG. 1 illustrates an inventive commercial refrigeration network 10 diagrammatically. The commercial refrigeration network 10 includes a plurality of modular refrigeration system units 14 constructed and arranged for placement in strategic proximity to corresponding product cooling zones within a commercial space 18 (e.g., a foodstore, supermarket, etc.). The location of the refrigeration units 14 may be within or remote from a customer shopping area 22 of the commercial space 18. In FIG. 1, two modular refrigeration units 14A and 14B are shown within the shopping area 22, and one modular refrigeration unit 14C is shown outside of the shopping area 22. Each refrigeration system unit 14, or merchandiser, includes at least one linear compressor 22 (shown in FIG. 2) and is sized to efficiently maintain its associated discrete cooling zone at optimum refrigeration temperatures. Each of the cooling zones comprises one or more of the store coolers, freezers, preparation rooms or display merchandisers. A cooling zone is typically an area, department, or lineup of merchandising fixtures operating at substantially the same temperature.

The refrigeration network 10 includes a coolant circulating system 30 constructed and arranged to circulate a cooling fluid or coolant from a remote source 34 to a respective refrigeration unit condenser/heat exchanger 38. The circulation of a controlled coolant in a heat exchange relationship with the unit condensers provides optimum condensing and refrigeration efficiency of the evaporators in cooling their respective product zones. The coolant system 30 derives a cooling liquid, such as chemically treated water or a glycol solution, from one or more sources 34 and circulates the cooling liquid by at least one pump 42 through a distribution arrangement. In the illustrated embodiment, the distribution arrangement includes a distribution manifold 46 and branch coolant delivery lines or conduits 50 to the condenser/heat exchanger 34 of each modular unit 14. For example, and as shown in FIGS. 2, 3, and 16, a secondary fluid (e.g., a liquid) provided by the fluid-input line 50, or conduits, cools the condenser 38. At least two alternate cooling sources 34A, 34B are illustrated as an arrangement to assure a back-up condenser cooling system. Branch return conduits 54, or a fluid-output, and a return manifold 58 carry away the coolant fluid with the exchanged heat of rejection from the respective refrigeration unit condensers 38 for dissipation externally of the shopping area 22.

The coolant sources 34A, 34B, 34C, 34D may be a single fluid cooling apparatus, such as a closed or open loop roof top cooling tower, a ground source water supply, a dedicated normal temperature refrigeration system, a chiller system or recirculating water source, or a combination of such alternate fluid cooling sources to assure a continuous supply of coolant at a substantially constant temperature, as will be discussed below. In an embodiment including multiple modular refrigeration units 14, the refrigeration units 14 derive their respective condenser cooling from a common liquid cooling source 34 remote from the modular refrigeration units 14 in the shopping area 22. In one embodiment, the heat exchanger is of the plate-to-plate type for optimal heat transfer of the heat of rejection transferred from the product zone through the unit condensers 38 to the coolant, which then carries the cumulative heat load in a heated coolant return mode for dissipation externally of the shopping area 22. It will be readily apparent to those skilled in the art that the heat of rejection and the heat of compression from the linear compressors may be utilized for seasonal heating of the supermarket.

As will be discussed further below, the fluid can also be used to cool other components of the refrigeration unit 14. In other embodiments, the merchandiser 14 includes a fan if the condenser 38 is air-cooled.

The modular nature of the refrigeration units 14 utilizes three basic variable forms of the refrigeration unit 14: a vertical compressor configuration, such as 14C (shown in FIGS. 1, 11, 12); a horizontal compressor configuration, such as 14B (shown in FIGS. 1, 2, 9, 13, 15); and a combination or mixed horizontal and vertical compressor configuration, such as 14A (shown in FIGS. 1, 12, 16).

During a refrigeration cycle, the linear compressor 26 compresses a refrigerant, resulting in the refrigerant increasing in temperature and pressure. The compressed refrigerant is sent out of the linear compressor 26 as a high-temperature, high-pressure heated gas. The refrigerant travels to a condenser 38 (shown in FIG. 2). The condenser 38 changes the refrigerant from a high-temperature gas to a warm-temperature gas/liquid, which maintain the associated discrete cooling zones at an optimum refrigeration temperature. As discussed above, air and/or a liquid are used to help the condenser 38 with this transformation.

FIG. 2 is a schematic flow diagram of a modular refrigeration unit 14 and coolant circulating system 30. In FIG. 2, each of the modular refrigeration units 14 includes a refrigeration rack 62 constructed and arranged to mount and support the operative components of a closed refrigeration circuit 66. The closed refrigeration circuit 66 is dedicated to refrigeration load requirements of its associated discrete product cooling zone 68. In the illustrated embodiment, the refrigeration rack 62 includes four linear compressors 26 connected in parallel. In further embodiments, at least one and up to ten linear compressors 26 may be included in the refrigeration unit 14 and supported by the refrigeration rack 62. The linear compressors 26 are connected by a discharge header 70 to a diverting valve 74. The diverting valve 74 selectively connects the discharge header 70 to a heat recovery means, such as a heat reclaim coil 78 or a hot water exchanger (not shown), or directly to the system condenser 38 located on the refrigeration rack 62. In the illustrated embodiment, a liquid receiver 82 is connected to the condenser 38 to receive the condensate outflow from the condenser 38.

The high side of the refrigeration circuit 66 is connected by liquid lines 86 to evaporative expansion valves 90 at each evaporator 94 associated with a discrete product cooling zone 68 to be cooled. On the low side, the refrigerant expands and vaporizes in the merchandiser evaporators 94 removing heat from the product zone 68 to maintain the preselected desired cooling. The outlets of the evaporators 68 connect to a common suction header or manifold 98. The suction manifold 98 connects to the suction side of the compressors 26 to complete the refrigeration circuit 66. It will be readily apparent to those skilled in the art that individual modular refrigeration units 14 may generally include other system components, such as defrost system means, system performance sensing and operating control panel, microprocessor apparatus, alarm systems and the like.

FIG. 2 illustrates a unit heat reclaim coil 78 as part of the closed refrigeration circuit 66 of the refrigeration unit 14. Such a heat reclaim coil 78 is generally housed in a conventional store air handler (not shown) for seasonal air conditioning and environmental heating of the store, but may be located remotely as a water heating unit (not shown). Due to the modularity of the refrigeration units 14 and their proximate location to their respective cooled product zones, it is contemplated that unit heat reclaim coils 78 may be strategically located under selected merchandisers or the like for environmental shopping arena heating. It will be readily apparent that a heat reclaim coil 78 is typically designed to function as a pre-condenser that removes heat from the compressed vaporous refrigerant on the high side upstream of the system condenser. The heat reclaim coil 78 does not reduce the refrigerant vapor to its saturated condensing temperature, because this is the final function of the condenser 38 at the unit heat exchanger.

The use of linear compressors 26 in the refrigeration units 14 provides for oil-free operation of the refrigeration system and gives performance and cost advantages over existing systems. Linear compressors 26 used in the refrigeration units 14 eliminate the need for oil management components (such as oil separators, oil controls, oil safety devices, etc) within the refrigeration system. Heat transfer within the refrigeration system is improved due to the absence of an oil film on evaporator and condenser surfaces. Further, installation costs are lower due to the elimination of the need for suction traps. The use of linear compressors 26 in the refrigeration units 14 also provides for continuously variable capacity of the refrigeration loads from about 30% to 100% (discussed below with respect to FIGS. 6-8), as compared to existing systems utilizing scroll compressors.

In the embodiment illustrated in FIG. 2, the modular refrigeration unit 14 is strategically placed in the commercial space 18 in close proximity to the dedicated cooling zone 68 of an associated merchandiser department or case lineup. In another embodiment illustrated in FIG. 3, the components of the closed refrigeration circuit 66 are located remotely of the dedicated cooling zone 68, such as in a service area 102 (shown in FIG. 5) of the commercial space 18. In some embodiments, the closed refrigeration circuit components, including the linear compressors 26, are not arranged on a refrigeration rack and instead are positioned separately to form the closed refrigeration circuit 66.

In another embodiment illustrated in FIG. 4, the modular refrigeration unit 14 includes an air cooled condenser 38 located remotely of the refrigeration rack 62, for example on a roof of the commercial space 18. A fan 100 mounted to or within the condenser 38 provides cooling to the refrigerant passing through the condenser. An air cooled condenser is an alternative cooling means from the coolant circulating system 30 shown in FIGS. 2 and 3. In further embodiments, the air cooled condenser 38 may be located remotely from the commercial space 18 or in the service area 102 of the commercial space 38.

FIG. 5 is a representative supermarket floor plan illustrating the strategic placement of dedicated modular refrigeration system units 14 relative to the respective refrigeration loads, as well as refrigeration units 14 located remotely from the respective refrigeration loads in a service area 102 of the commercial space 18. In the embodiment illustrated in FIG. 5, refrigeration unit 14A is a medium temperature system servicing the produce department merchandisers 68A operating at temperatures in the range of about 45° F. to about 50° F. (see also FIG. 9). Refrigeration unit 14B is a low temperature system dedicated to maintain ice cream product temperatures of about −20° F. in twin island “coffin” type merchandisers 68B in the shopping area 22. Although the refrigeration unit 14B is located in the service area 102, in further embodiments it may be located proximate the merchandisers 68B (see also FIG. 13). Refrigeration unit 14C is a low temperature system for a dual back-to-back lineup of frozen food reach-in merchandisers 68C within the shopping area 22 (see also FIG. 11). Refrigeration unit 14D is a low temperature system dedicated to maintain frozen meat products in a meat freezer (cooling zone 68D) located in the service area 102 outside of the shopping area 22. Refrigeration unit 14E is a medium temperature system located in the service area 102, but immediately adjacent to its discrete service load of multi-deck meat merchandisers 68E in the shopping area 22. Refrigeration unit 14F is a medium temperature system for a lineup of non-frozen reach-in product fixtures 68F in the shopping area 22. Refrigeration unit 14G is a medium temperature system also located in the service area 102, but constructed and arranged to service both a deli walk-in cooler 68G1 in the service area 102 and a deli merchandiser lineup 68G2 in the shopping area 22. Refrigeration unit 14H is a medium temperature system for servicing a line of multi-deck produce merchandisers 68H. In the illustrated embodiment, the refrigeration unit 14H is located in the service area 102, however, in another embodiment the refrigeration unit 14H is located proximate the merchandisers 68H (see also FIG. 11). Refrigeration unit 14I is a low temperature system dedicated to an ice cream walk-in freezer 68I in the service area 102. Finally, refrigeration unit 14J is a medium temperature system associated with a dairy department lineup of multi-deck merchandisers 68J. In the illustrated embodiment, refrigeration unit 14J is located in the service area 102, however, in another embodiment the refrigeration unit 14J is located proximate the merchandisers 68J.

It will be readily apparent to those skilled in the art that a typical supermarket layout may also include a refrigerated floral merchandiser, an in-store bakery with coolers and retarder units, a seafood department and other non-refrigerated departments, dry goods shelving, customer checkout area and the like. As illustrated in FIG. 5, the conventional compressor machine room of existing supermarkets is eliminated in favor of the modular refrigeration units 14A-14J strategically located in and around the shopping area 22 and in the service area 102 of the commercial space 18. The refrigeration units 14 are specifically dedicated to discrete refrigeration loads. Those refrigeration units 14 located in close proximity to an associated group of storage or display merchandising zones operate at the same temperature and form the discrete load. In further embodiments, the service area 102 of the commercial space 18 may have a separate compressor machine room (not shown) for housing the linear compressors 26. However, the use of linear compressors 26 results in virtually no vibration, therefore, the need for a separate space to acoustically isolate the compressors is not necessary.

As described herein, the refrigeration systems, refrigeration units, and merchandisers include at least one linear compressor 26. It is envisioned that, in some embodiments, the linear compressor is a free-piston linear compressor, and in at least on envisioned embodiment, the free-piston linear compressor is a dual-opposing, free-piston linear compressor. A dual-opposing, free-piston linear compressor is obtainable from Sunpower, Inc. (Athens, Ohio, USA). Another example of a dual-opposing, free-piston linear compressor is disclosed in U.S. Pat. No. 6,641,377, issued Nov. 4, 2003, the content of which is incorporated herein by reference.

The free-piston linear compressor has some basic differences over conventional rotary compressors. The free-piston device is driven by a linear motor in a resonant fashion (like a spring-mass damper) as opposed to being driven by a rotary motor and mechanical linkage. One advantage with the linear motor is that the side loads are small, which greatly reduces friction and allows use of simple gas bearings or low-viscosity oil bearings. In addition, since friction has been greatly reduced, the mechanical efficiency of the device is greater, internal heat generation is lower, and acoustic noise is reduced. Additionally, inherent variable piston stroke allows for efficient capacity modulation over a wide range. For example, linear compressors have continuously variable capacity from about 30% to 100% by adjusting piston stroke. In constructions having dual-opposing pistons, the pistons vibrate against each other (i.e., provide a mirrored system) to virtually cancel all vibration. This reduces the acoustic noise of the linear compressor even further than a single piston linear compressor.

FIGS. 6, 7, and 8 show three sectional views of a dual-opposing linear compressor 110 capable of being used with the modular refrigeration systems, refrigeration units and merchandisers described above. FIG. 6 shows the compressor 110 at an intake stroke, FIG. 7 shows the compressor 110 at neutral, and FIG. 8 shows the compressor 110 at a compression stroke. As shown in FIGS. 6-8, the dual-opposing linear compressor 110 includes a housing 114 supporting a main body block 118. Inner and outer laminations 122 and 126 are secured to the main body block 118 and coils 130 are wound on the outer laminations 126, thereby forming stators. The stators, when energized, interact with magnet rings 134 mounted on outer cylinders 138. The outer cylinders 138 are fastened to pistons 142, which are secured to springs 146. The interaction between the magnet rings 134 and the energized stators results in the outer cylinders 138 moving the pistons 142 linearly along an axis of reciprocation 150.

When the pistons 142 are at the intake stroke, refrigerant is allowed to flow from a suction port 154 through channels 158 into a compression space 162 (best shown in FIG. 6). When moving from the intake stroke to the compression stroke, valves 166 (best shown in FIG. 7) close the channels, and the refrigerant is compressed out through discharge valve 170 and discharge port 174 (best shown in FIG. 8). The linear motor allows for variable compression (e.g., from approximately 30% to 100%) by the pistons 142, and therefore, the linear compressor 110 provides variable capacity control. In other words, the linear motors can cause the pistons 142 to move a small stroke for a first volume, or to move a larger stroke for a second, larger volume. The linear compressors 110 provide a variable refrigeration capacity (e.g., by varying piston stroke) balanced to the refrigeration loads imposed by the associated product cooling zones 68. Accordingly, the refrigeration units 14 allow for variable loads, decrease compressor cycling, and reduce temperature swings.

In some embodiments, the linear compressor 110 includes a jacket 178 (shown in phantom) enclosing at least a portion of the housing 114. The jacket 178 includes a fluid-input port 182 and a fluid-output portion 186, and provides a plenum 190 containing a cooling fluid, thereby providing a fluid-cooled compressor. Other arrangements for cooling the compressor with a fluid are possible.

An example of a compressor controller for use with the dual-opposing, free-piston linear compressor shown in FIGS. 6-8 is disclosed in U.S. Pat. No. 6,536,326, issued Mar. 25, 2003, the content of which is incorporated herein by reference. It is also possible for the coolant fluid to be used for cooling a controller 192 (shown in FIG. 11). Similar to the linear compressor, a jacket having input and output ports can be used to surround a housing of the controller.

An example of refrigeration unit 14A and its associated refrigerated zone 68A is illustrated in FIGS. 9 and 9A. The cooling zone illustrated is a medium temperature produce section or department 194 of a supermarket. The illustrated cooling zone 194 includes two refrigerated produce tables 194A, one unrefrigerated produce table 194B (used for products not requiring refrigeration), and one or more lineups of multi-deck or gondola produce merchandisers 194C. The refrigeration unit 14A may be concealed under one of the refrigerated tables 194A, in the base of the unrefrigerated produce table 194B, or in a merchandiser lineup 194C. The refrigeration unit 14A may be accessed by removing a front panel of the merchandiser, or by constructing and arranging a table top of the merchandiser to be hinged for vertical lifting movement or for horizontal side movement thereon. In the illustrated embodiment, the refrigeration rack 62 is constructed and arranged to support four linear compressors 26 in a combination arrangement of two pairs of horizontally disposed compressors in side-by-side relationship. The linear compressors are connected in parallel and may be operated individually, cyclically or variably to keep the merchandiser temperatures constant. FIG. 9A shows that the condenser 38 of the modular unit 14A is part of a heat exchanger 198 containing a coolant loop having cool coolant delivery mode 50 and a warm coolant return mode 54.

FIG. 10 is an alternate configuration of the cooling zone 194 shown in FIG. 9. FIG. 10 illustrates a refrigeration system having refrigeration components located remotely of the associated refrigerated zone 68A. The refrigeration components may be located on a refrigeration rack 62 or positioned independently to form the closed refrigeration circuit 66. Referring to FIGS. 9 and 10, a discharge conduit 202 connects the compressor head manifold 70 (i.e., discharge header) to the unit condenser 38 on the refrigeration rack 62. The condenser 38 connects through the system receiver-accumulator 82 (shown in FIG. 2) to the liquid line conduits 86 that extend in short runs from the refrigeration unit 14A beneath the floor to the evaporators 94 in the merchandisers 194. A suction conduit 206 returns the vaporized refrigerant liquid to the compressors 26. In the illustrated embodiment, a coolant delivery line 50 from the remote cooling liquid source 34 (shown in FIG. 1) is piped beneath the floor or overhead to the refrigeration rack 62 for removing the heat of rejection and compression from the unit condenser 38 in the heat exchanger 198. Further, a coolant return line 54 is provided to expel this heat to a location exterior of the supermarket. In a further embodiment of the refrigeration unit 14A shown in FIGS. 9 and 10, the condenser is air cooled and located remotely of the refrigeration unit 14A.

Additional configurations of the linear compressors 26 accommodated by the modular refrigeration racks 62 and their associated discrete refrigeration loads are shown in FIGS. 11-14. In each embodiment, all of the closed refrigeration circuit components are rack mounted except for the merchandiser 68 or other zone evaporators 94 and associated refrigerant control and sensing means. Examples of other equipment not mounted on the refrigeration rack include expansion valves 90 and defrost control valves (not shown), as well as connecting discharge and suction lines between the evaporators and the refrigeration system racks.

In FIG. 11, the modular refrigeration unit 14 utilizes a vertical linear compressor unit that is positioned behind a shelving unit 210. The shelving unit 210 is arranged to cover one side of the modular refrigeration unit 14 when positioned at the end of a merchandiser lineup, such as the open front multi-deck merchandisers 214 shown in FIG. 11. FIG. 12 illustrates lineups of reach-in merchandisers, such as merchandiser 68F, in which the modular refrigeration units and refrigeration racks are interposed into the middle of the lineups. In FIG. 12, the refrigeration unit 14F includes a vertical stack of linear compressors 26.

FIG. 13 illustrates another configuration of a horizontal linear compressor unit centrally located between parallel rows or twin island coffin merchandisers 68B of the type used for ice cream or other frozen products. The three linear compressors 26 are arranged on a horizontal line in the modular refrigeration unit 14B and at least one exterior side of the refrigeration rack 62 has a removable panel 218 that can be replaced after service. In the embodiment illustrated in FIG. 14, the refrigeration unit 14B and the refrigeration rack 62 are positioned remotely from the parallel rows or twin island coffin merchandisers 68B, oftentimes in a service area 102 (shown in FIG. 5) of the commercial space 18.

The location of the modular refrigeration units 14, whether in the shopping area 22 or in the service area 102 of the commercial space 18, are in close proximity to the associated refrigeration loads serviced by the respective units. Such placement greatly reduces the amount of refrigerant needed and the length of piping needed to carry the refrigerant to all the product merchandisers. The placement of the refrigeration units 14 in the shopping area 22 is commercially feasible only if the acoustic noise from the compressors is substantially eliminated or reduced to acceptable decibel levels. As discussed above, the use of linear compressors in the refrigeration units reduces the acoustic noise of the refrigeration unit and virtually cancels all vibration of the unit, as compared to compressors used in prior art systems.

The modularity of the refrigeration racks 62 for forming variant refrigeration unit arrangements is described with respect to FIGS. 15 and 15A. In the illustrated embodiment, the refrigeration rack 62, for a horizontal linear compressor unit, includes a series of similar frame modules 220. Each frame module 220 includes a main frame having lower or first level horizontal structural members 224 forming a rectangular base and vertical struts 228, or stanchions, located at the corners of the base 224. FIGS. 15 and 15A illustrate a four linear compressor unit with three frame modules 220 joined together. The two leftward modules also include upper or second level horizontal structural member 232 secured to the vertical stanchions 228 in spaced relation above the lower base level 224. Each frame module 220 is provided with a horizontally extending metal support or mounting plate 236 that is preformed to receive and secure specific components of the closed refrigeration system. In the illustrated embodiment, the leftward mounting plates 236A are each constructed and arranged to mount two linear compressors 26. It will be readily apparent that the condenser/heat exchanger 38 and the receiver 82 are also accommodated by the modular refrigeration rack arrangement. The rightward unit 236B is designed to mount a control panel 240 for operating the associated refrigeration system of the modular refrigeration unit.

It will also be readily apparent to those skilled in the art that the same base frame module 220, lower level base frame 224, vertical struts 228, second level frame 232, and mounting plate 236 may be used to form a vertically arranged refrigeration rack or a combination refrigeration rack. The embodiment shown and described with respect to FIGS. 15 and 15A is illustrative only. The refrigeration rack may assume other configurations, such as a vertical linear compressor arrangement in which single linear compressors 26 are stacked one above the other in a tier that affords a minimum floor space footprint and excellent accessibility for service.

The modular refrigeration unit 14 includes a single electrical junction to the refrigeration rack that permits the connection of all system components as well as local wiring control over the ancillary merchandiser electrical equipment (e.g., lighting, fans, antiswear heaters) for wiring from the same location. Only a single power circuit is required to extend from a remote power source (not shown) to the unit junction box usually associated with the control panel 240. In the illustrated embodiment, the junction box is connected to the control panel that contains a remotely activated contactor and circuit breaker system for providing distributed electrical power via buss arrangement to the electrical components in the system.

In one embodiment, each of the modular refrigeration units is monitored and controlled by a personal computer linked to a microprocessor within the control panel 240. The control system is conventional, except that the linear compressors are located around the commercial space, and are supplemented by individual control systems (i.e., microprocessors) associated with each rack. Interrogation of individual units to diagnose problems and override of the general control functions for purposes of testing and repair is accomplished at the specific refrigeration units. To reduce duplication of components such as visual system readouts on each control panel, it is envisioned that a hand-held monitor would be used to plug into the microprocessor and provide a visual readout of its settings and conditions.

The modularity of the refrigeration units 14 and the refrigeration racks 62 reduces the time and cost of installing the refrigeration system network and simplifies service, as compared to conventional back room refrigeration systems. Further, since the alternate configurations of the refrigeration units and racks are pre-designed, less field assembly of conduit joints are required. The flexibility in the modular refrigeration units permits the dedicated units to be located unobtrusively within a public area of a commercial space, such as a supermarket, in such a way as to blend with the closely adjacent configurations of refrigerated product storage coolers and display merchandisers having the associated cooling zones.

FIG. 16 shows a self-contained refrigeration unit 250, or merchandiser. The refrigeration unit 250 is shown as an open-unit display merchandiser having a single display fixture 254. However, other types of merchandisers (e.g., a glass-door display merchandiser, a vending machine, a dispenser, etc.) can embody the invention. Also, it is envisioned that the merchandiser 250 can include more than one display fixture (e.g., is a combination merchandiser). As used herein, the term “self-contained refrigeration unit” means a refrigeration unit where the frame of the unit supports the linear compressors 26, the condenser 38, the expansion valve 90, and the evaporator 94.

With reference to FIG. 16, the merchandiser 250 includes a frame 258 supporting the display fixture 254 and the components providing the refrigeration cycle (discussed below). As used herein, the term “frame” is broadly defined as something composed of parts fitted together and united. The frame 258 includes the housing of the unit, the one or more components of the refrigeration cycle, and/or the display fixture. Alternatively, the frame 254 provides the foundation for the housing, the one or more components of the refrigeration cycle, and/or the display fixture. The display fixture 254 comprises a cabinet, case, container or similar receptacle adapted to accommodate a commodity. The fixture 254 includes at least one surface 262 that at least partially defines an environmental space. For a “glass-door” display merchandiser, at least one of the surfaces defining the environmental space is partially defined by a translucent material.

It should be noted that some merchandisers do not include a display fixture, however, the refrigeration unit still includes at least one surface at least partially defining an environmental space. Also the refrigeration unit 250 can include multiple environmental spaces. As used herein, the term “environmental space” is a three-dimensional space (defined at least in part by the at least one surface) where the environment is controlled by the refrigeration unit. For example, the refrigeration unit 250 of FIG. 16 consists of two environmental spaces 266 and 270, where the temperatures of the environmental spaces are controlled by the components of the refrigeration cycle. Other characteristics (e.g., humidity) of the environmental spaces 266 and 270 can be controlled.

As shown in FIG. 16, the components forming the refrigeration cycle comprises the linear compressor 26, the condenser 38, the expansion device 90 (also typically referred to as the expansion valve), and the evaporator 94, all of which are in fluid communication. Of course, in further embodiments, the refrigeration cycle can include other components, such as the receiver 82 or a filter (not shown).

The refrigeration unit includes the controller 192 that controls the refrigeration unit. The controller 192 includes one or more temperature sensors and/or one or more pressure sensors (only one sensor 274 is shown) coupled to the refrigeration unit. The controller also includes a user-input device. The controller 192 receives refrigeration unit input information (i.e., signals or data) from the sensor(s) 274, receives user input (e.g., temperature settings) from the user input device, processes the inputs, and provides one or more outputs to control the refrigeration unit (e.g., to control the compressor, control the expansion device, control a defrost system, etc.). In further embodiments, the controller 192 is used with other refrigeration units or merchandisers and may be located in the control panel 240 of such units.

For the refrigeration unit shown, the controller 192 includes the compressor controller. However, the refrigeration unit controller 192 can be separated into multiple controllers (e.g., a controller for overall control and a compressor controller), which is typically referred to as a distributed control system. An example of a distributed control system is disclosed in U.S. Pat. No. 6,647,735, issued Nov. 18, 2003, the content of which is incorporated herein by reference.

In one embodiment, the controller 192 includes one or more programmable devices (e.g., one or more microprocessors, one or more microcontrollers, etc.) and a memory. The memory, which can include multiple memory devices, includes program storage memory and data storage memory. The one or more programmable devices receive instructions, receive information (either directly or indirectly) from the devices in communication with the programmable devices, execute the instructions, process the information, and communicate outputs to the attached devices.

The user-input device is shown in FIG. 16 as a user interface 278. The user-input device can be as simple as a thermostat dial. Other user-input devices include push-buttons, switches, keypads, a touch screen, etc. The user interface 278 also includes a user-output device (e.g., a LCD display, LEDs, etc.). In another embodiment, the user interface 278 includes connections for communication to other interfaces or computers or is located in the control panel 240 of the refrigeration unit.

It is envisioned that the controller 192 can use at least one of a sensed pressure and a sensed temperature to control the linear compressor, the expansion device, and/or the fans. By controlling these components, the controller 192 thereby controls the temperature of the environmental space(s) of the refrigeration unit. For example, the controller 192 can include a temperature sensor that senses discharge air temperature. If the discharge air temperature is outside of a predetermined temperature range (e.g., set by an operator), the controller 192 can modulate or change the volume of the compressor (e.g., increase or decrease the stroke of the pistons of the compressor). How the controller 192 changes the compressor volume can be based on empirical test data. Other methods known to those skilled in the art for controlling the compressor are possible. Other parameters used by the controller 192 for controlling the compressor can include suction temperature, suction pressure, discharge pressure, evaporator air exit temperature, evaporator surface temperature, evaporator pressure, the temperature difference between discharge and return air temperature, product zone temperature, product simulator temperature, and similar parameters.

Various other features and advantages of the invention are set forth in the following claims. 

1. A modular commercial refrigeration unit constructed and arranged for placement in strategic proximity to a plurality of associated product cooling zones within a shopping area, the modular refrigeration unit comprising: a refrigeration rack proximate to a shopping area and configured to accommodate maximum refrigeration loads of the associated product cooling zones and having an optimum footprint, wherein the refrigeration rack is constructed to support components of a closed refrigeration circuit including associated high side and low side refrigerant delivery and suction means extending from the rack and being operatively connected to a plurality of evaporators for cooling the associated product cooling zones; a linear compressor; and a cooling source remote from the refrigeration unit provides a cooling relationship with a condenser for providing optimum condensing and efficiency of the evaporators in cooling the associated product cooling zones.
 2. The modular refrigeration unit of claim 1 wherein the closed refrigeration circuit includes a plurality of linear compressors.
 3. The modular refrigeration unit of claim 2 wherein the linear compressors are connected in parallel.
 4. The modular refrigeration unit of claim 1 wherein the linear compressor provides a variable refrigeration capacity balanced to the refrigeration loads imposed by the associated product cooling zones.
 5. The modular refrigeration unit of claim 4 wherein the variable refrigeration capacity is in the range of about 30% and 100%.
 6. The modular refrigeration unit of claim 1 wherein the linear compressor comprises a free-piston linear compressor including dual-opposing pistons.
 7. The modular refrigeration unit of claim 1, and further comprising a controller to control the operation of the linear compressor wherein the controller comprises a sensor configured to sense a parameter representative of an operating condition associated with the modular refrigeration unit, and wherein the controller is operable to control the linear compressor based at least in part on the sensed parameter.
 8. The modular refrigeration unit of claim 7 wherein the linear compressor comprises a free-piston linear compressor comprising dual-opposing pistons, and wherein the controller is operable to control the linear compressor by being further operable to control the stroke of the pistons for varying the effective displaced volume of refrigerant based at least in part on the sensed parameter.
 9. The modular refrigeration unit of claim 1 wherein the linear compressor is located remote from the shopping area.
 10. The modular refrigeration unit of claim 1 wherein the linear compressor is mounted on the refrigeration rack.
 11. The modular refrigeration unit of claim 1, and further comprising a condenser connected between the linear compressor and receiver means of the refrigeration circuit.
 12. The modular refrigeration unit of claim 11 wherein the condenser is mounted on the refrigeration rack.
 13. The modular refrigeration unit of claim 11 wherein the condenser is air cooled.
 14. The modular refrigeration unit of claim 1 wherein the cooling source provides a heat exchange relationship with the condenser for providing optimum condensing and efficiency of the evaporators in cooling the associated product cooling zones.
 15. A modular refrigeration system comprising: at least two refrigerated fixtures having first closely adjacent locations in a shopping area; at least one evaporator coil for cooling the refrigerated fixtures to maintain products therein within a predetermined temperature range; a linear compressor having a second location in close proximity to the refrigerated fixtures; a condenser connected together with the linear compressor and the evaporator coils to form a closed loop refrigeration circuit; a heat exchange device located remote from the shopping area for transferring heat to an exterior atmosphere; and a closed heat transfer loop extending between the closed loop refrigeration circuit and the remote environment and interconnecting the heat exchange device and the condenser in continuous communication to transfer heat from the condenser to the heat exchange device.
 16. The refrigeration system of claim 15 wherein the second location is in the shopping area closely adjacent to the refrigerated fixtures.
 17. The refrigeration system of claim 15 wherein the second location is remote from the shopping area.
 18. The refrigeration system of claim 15 wherein the closed loop refrigeration circuit includes a plurality of linear compressors.
 19. The refrigeration system of claim 18 wherein the linear compressors are connected in parallel.
 20. The refrigeration system of claim 15 wherein the linear compressor provides a variable refrigeration capacity balanced to the refrigeration loads imposed by the associated refrigerated fixtures.
 21. The refrigeration system of claim 20 wherein the variable refrigeration capacity is in the range of about 30% and 100%.
 22. The refrigeration system of claim 20 wherein the linear compressor comprises a free-piston linear compressor including dual-opposing pistons.
 23. The refrigeration system of claim 22 wherein the variable refrigeration capacity is controlled by varying stroke of the pistons.
 24. The refrigeration system of claim 15, and further comprising a controller coupled to the linear compressor, the controller comprising a sensor configured to sense a parameter representative of an operating condition associated with the refrigerated fixtures, and wherein the controller is operable to control the linear compressor based at least in part on the sensed parameter.
 25. A commercial refrigeration network comprising: a first modular refrigeration system unit in close strategic proximity to a first refrigerated product zone, the first modular refrigeration system unit including a first refrigeration rack comprising first closed refrigeration circuit components including a linear compressor, high side receiver means and associated high side and low side refrigerant delivery, and suction means operatively connected to a first evaporator for cooling the first refrigerated zone, and the first modular refrigeration system unit also including a first condenser connected between the linear compressor and receiver means of the first closed refrigeration circuit; at least one other modular refrigeration system unit in close strategic proximity to an associated other refrigerated product zone, and including an other refrigeration rack comprising other closed refrigeration circuit components including a linear compressor, high side receiver means and associated high side and low side refrigerant delivery, and suction means operatively connected to an other evaporator for cooling the other refrigerated zone, and the other modular refrigeration system unit also including an other condenser connected between the linear compressor and receiver means of the other closed refrigeration circuit; and a cooling source provides a cooling relationship with the first and other condensers for the respective first and other refrigeration system units.
 26. The refrigeration network of claim 25 wherein the first and other refrigerated product zones are located within a shopping area at spaced locations therein, and the dedicated first and other refrigeration racks are closely associated with the respective product zones adjacent to their respective locations.
 27. The refrigeration network of claim 25 wherein the refrigerated product zones comprise a plurality of merchandisers located in the shopping arena, the plurality of merchandisers comprising: first merchandisers incorporating the first evaporator and associated first refrigerant control means and first refrigeration sensing means; and other merchandisers incorporating the other evaporator and associated other refrigerant control means and other refrigeration sensing means.
 28. The refrigeration network of claim 25 wherein at least one of the modular refrigeration system units includes a plurality of linear compressors.
 29. The refrigeration network of claim 28 wherein the linear compressors are connected in parallel.
 30. The refrigeration network of claim 25 wherein the linear compressors provide a variable refrigeration capacity balanced to the refrigeration loads imposed by the associated refrigerated zones.
 31. The refrigeration network of claim 30 wherein the variable refrigeration capacity is in the range of about 30% and 100%.
 32. The refrigeration network of claim 25 wherein each modular refrigeration system unit further comprises a controller coupled to the linear compressor, the controller comprising a sensor configured to sense a parameter representative of an operating condition associated with the modular refrigeration unit, and wherein the controller is operable to control the linear compressor based at least in part on the sensed parameter.
 33. The refrigeration network of claim 32 wherein each linear compressor comprises a piston, and wherein the controller is operable to control the linear compressor by being further operable to control the stroke of the piston based at least in part on the sensed parameter.
 34. The refrigeration network of claim 32 wherein each linear compressor comprises a free-piston linear compressor comprising dual-opposing pistons, and wherein the controller is operable to control the linear compressor by being further operable to control the stroke of the pistons for varying the effective displaced volume of refrigerant based at least in part on the sensed parameter.
 35. The refrigeration network of claim 25 wherein the cooling source comprises a plurality of cooling sources, each cooling source mounted to a respective one of the first and other condensers.
 36. The refrigeration network of claim 25 wherein the cooling source comprises a coolant circulating system having a plurality of heat exchanger circuits in heat exchange relationship with the respective first and other condensers for the respective first and other refrigeration system units, the coolant circulating system having at least one continuous cooling source for coolant in the circulating system.
 37. A commercial refrigeration network comprising: a first refrigeration merchandiser comprising at least one first surface at least partially defining a first environmental space adapted to accommodate a commodity, first closed refrigeration circuit components including a free-piston linear compressor, a condenser, an expansion device, and an evaporator in fluid communication wherein the evaporator is in thermal communication with the environmental space to influence the temperature of the environmental space, and a first frame supporting the at least one first surface, the linear compressor and the evaporator; at least one other refrigeration merchandiser comprising at least one other surface at least partially defining an other environmental space adapted to accommodate a commodity, other closed refrigeration circuit components including a free-piston linear compressor, a condenser, an expansion device, and an evaporator in fluid communication wherein the evaporator is in thermal communication with the environmental space to influence the temperature of the environmental space, and an other frame supporting the at least one other surface, the linear compressor and the evaporator; and a cooling source provides a cooling relationship with the first and other condensers for the respective first and other refrigeration system units.
 38. The refrigeration network of claim 37 wherein the first frame also supports the condenser and the expansion device and the other frame also supports the condenser and the expansion device.
 39. The refrigeration network of claim 37 wherein at least one of the refrigeration merchandisers includes a plurality of linear compressors.
 40. The refrigeration network of claim 39 wherein the linear compressors are connected in parallel.
 41. The refrigeration network of claim 37 wherein the linear compressor provides a variable refrigeration capacity balanced to refrigeration loads imposed by the refrigeration merchandiser.
 42. The refrigeration network of claim 41 wherein the variable refrigeration capacity is in the range of about 30% to 100%.
 43. The refrigeration network of claim 41 wherein the linear compressor comprises dual-opposing pistons.
 44. The refrigeration network of claim 43 wherein the variable refrigeration capacity is controlled by varying stroke of the pistons.
 45. The refrigeration network of claim 37 wherein the cooling source comprises a plurality of cooling sources, each cooling source mounted to a respective one of the first and other condensers wherein the first and other condensers are air cooled.
 46. The refrigeration network of claim 37 wherein the cooling source comprises a coolant circulating system having a fluid input line and a fluid output line in fluid communication with the respective first and other condensers for the respective first and other refrigeration merchandisers, the coolant circulating system having at least one continuous cooling source for coolant in the circulating system. 